It is to be expected that changes in the subcellular distribution of the mitochondrial enzymes lipoamide dehydrogenase (LIPDH), citrate synthase (CS) and β-Hdroxyacyl-CoA-dehydrogenase (HADH) in the muscle tissue give information on the type and the extent of damage of mitochondria during storage and treatment of meats; such changes may be also used as basis of methods for the differentiation between fresh and frozen/thawed meat. — Standard methods for the determination of the activities of LIPDH, CS, and HADH in tissue extract and muscle press juice are described. The influence of enzyme concentration, pH and temperature on the enzyme activities in muscle extract was investigated. Furthermore the error in the enzyme analyses by the standard methods was determined.